PURPOSE: To prevent exfoliation of an outside layer consisting of a WC sintered material by a strong and tough inside layer and to obtain a composite material which is highly resistant to wear and is economical by forming the inside layer of a casting material of the same kind or a different kind which is metallurgically continuous with an intermediate layer which is sintered continuously with the ouside layer and has the gaps among the sintered particles.
CONSTITUTION: A cylindrical sintered WC composite material 9 consisting of an outside layer 10 consisting of a sintered WC material having low void volume and an intermediate layer 11 prior to penetration consisting of a sintered WC material having high void volume formed continuously in the inside of the layer 10 is manufactured. A difference is given in the void volumes of the layer 10 and the layer 11 by using a thermoplastic binder which is expended in the preliminary sintering stage and WC powder having a large grain size in the part corresponding to the intermediate layer in the stage of molding the WC particles, etc. by compaction. Said material 9 is then fixed to the inside of a die 16 for centrifugal casting by refractories 12 and the die 16 is rotated. The molten metal of a desired casting material is poured through a trough 14 into the mold and the inside layer 15 is centrifugally cast.
HASHIMOTO TAKASHI
KATAYAMA HIROAKI
MORIKAWA TAKERU
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